The present invention relates to an apparatus for making and dispensing foam. More particularly this invention concerns such an apparatus used for making soap or detergent foam.
A standard pump-type soap dispenser has several disadvantages. It normally only puts out a small amount of concentrated soap or detergent with each actuation so the user normally actuates it a few times, taking substantially more than is really needed. Furthermore the devices are only usable in combination with a water faucet, as the concentrated soap or detergent simply cannot be conveniently spread around sufficiently to do the desired cleaning job. In addition such devices are often quite messy, dripping their sticky contents from the end of the dispensing spout when not in use.
Recourse has therefore been had to foam-generating and dispensing systems such as described in U.S. Pat. No. 6,053,364 of E. van der Heijden. This system has separate air and liquid pumps associated with complex valves that ensure that a charge of compressed air is combined with the liquid to form foam. Furthermore the seal system for the air pump is such that it has a very limited service life and, as a result, this system is normally made disposable so that once the supply of liquid soap is exhausted, the entire device with the pump is discarded.
It is therefore an object of the present invention to provide an improved apparatus for generating and dispensing foam.
Another object is the provision of such an improved apparatus for generating and dispensing foam which overcomes the above-given disadvantages, that is which is of simple construction yet which is of such durability that it can be refilled or the pump assembly can be reused with a new liquid supply.
An apparatus for making and dispensing foam has according to the invention a housing forming a generally closed foaming chamber, a liquid pump for drawing liquid from a supply and spraying the liquid into the foaming chamber, and an air pump for forcing air into the foaming chamber. A conduit forms a continuously open passage having an inner end opening into the foaming chamber and an outer end open to outside. A foam generator in the foaming chamber mixes the spray and air therein to generate foam and expand the foam to flow through the conduit out the outer end thereof.
Since the system works basically at atmospheric pressure, the sealing problems of the pressurized prior-art system are largely avoided. No outlet valve is needed to release foam when a predetermined pressure is reached, nor is a valve system between the two pumps. Furthermore the low-pressure operation of the system of this invention means that the user only needs to exert modest force to actuate the pumps. At the same time it is relatively easy, even at such low pressure, to produce a good soap foam. In fact the foam can be so voluminous that no water needs to be added to it for washing purposes, water only being needed for rinsing off.
The liquid pump in accordance with the invention includes a small-diameter liquid chamber and a small-diameter liquid piston displaceable therein and the air pump includes a large-diameter air chamber and a large-diameter air piston displaceable therein and coupled directly to the liquid piston. The supply is a vessel holding the liquid and to which the housing is removably attached. Thus the pump assembly can be used over and over with different soap/detergent containers in accordance with the commercially available xe2x80x9cingo-manxe2x80x9d system.
In accordance with the invention the air pump has an intake connected to the foaming chamber and draws air in through the conduit. The conduit, the air piston, and the air chamber are of such dimensions that displacement of the air piston between end positions moves a volume of air greater than a volume of air held in the conduit between its ends. Thus when the pumps return to their starting position, the air pump sucks back in any foam in the conduit so that nothing will drip from its end.
The air pump includes an unlubricated seal between the air piston and an inner surface of the air chamber. More particularly the seal is formed of a polyolefin, for example polyethylene (PE), low-density polyethylene (LDPE), polypropylene (PP), or an elastomer such as a thermoplastic elastomer (TPE), an acrylonitrile rubber (NBR), or ethylenepropylenediene rubber (EPDM).
The seal has a flexible lip engaging the surface at an acute angle. In the aspirating system the seal has a pair of oppositely directed flexible lips engaging the surface at acute angles for sealing in both directions. The air piston moves in a predetermined forward direction to move air from the air chamber into the foaming chamber and in the one-lip system the seal lip projects generally in the forward direction and engages the surface at an acute angle.
The foam generator according to the invention includes at least one sieve. In another system it has a pair of frustoconical foraminous sieves aligned with and flaring away from each other and can include a flat foraminous sieve aligned transversely between the frustoconical sieves. Alternately a pair of frustoconical foraminous sieves are aligned with each other and flare in a common direction. A sleeve having a pair of opposite ends each provided with a respective flat sieve can also form the foam generator.
The liquid pump can include a small-diameter liquid chamber opening directly into the foaming chamber, with no atomizing nozzle. Alternately the foam generator includes a nozzle connected between the liquid pump and the foaming chamber. The amount of air moved on operation of the system is 20 to 60 times greater than the amount of liquid moved, forming a light foam.
All parts of the housing, pumps, conduit, and foam generator that come into contact with the liquid or the foam are made of plastic. In addition a spring is braced between the housing and the pistons for urging same into respective end positions in each of which the respective chambers are at maximum volume. This spring can be wholly outside the structure so that, even though it is made of a corrosible steel, it is not exposed to the liquid.